methylmalonic aciduria due to methylmalonyl-CoA mutase deficiency
Findings
No curated finding names methylmalonic aciduria due to methylmalonyl-CoA mutase deficiency yet. Everything below is reference data from Mondo, HPO and GenCC, not evidence about what affects it.
Definition
Vitamin B12-unresponsive methylmalonic acidemia is an inborn error of vitamin B12 (cobalamin) metabolism characterized by recurrent ketoacidotic crises or transient vomiting, dehydration, hypotonia and intellectual deficit, which does not respond to administration of vitamin B12. There are two types of vitamin B12-unresponsive methylmalonic acidemia: mut0 and mut-.
Definition from the Mondo Disease Ontology (MONDO:0009612), read 2026-09-29. CC BY 4.0.
- Onset and course
- Infantile onset · Neonatal onset · Childhood onset
HPO, annotations 2026-09-02
Features
37 features
What the disease is reported to present with, and how often among people who have it — never how often a feature means the disease. HPO, annotations 2026-09-02.
- Decreased total neutrophil countHPOHP:0001875
- 1 of 1 reported patient
- Episodic metabolic acidosisHPOHP:0004911
- 1 of 1 reported patient
- HyperammonemiaHPOHP:0001987
- 1 of 1 reported patient
- Occasional (5% to 29% of cases)
- HypoglycemiaHPOHP:0001943
- 1 of 1 reported patient
- Methylmalonic acidemiaHPOHP:0002912
- 1 of 1 reported patient
- Methylmalonic aciduriaHPOHP:0012120
- 267 of 267 reported patients
- Respiratory distress
Show the remaining 25
- Nausea and vomitingHPOHP:0002017
- Very frequent (80% to 99% of cases)
- Respiratory insufficiencyHPOHP:0002093
- Very frequent (80% to 99% of cases)
- Decreased total leukocyte countHPOHP:0001882
- Frequent (30% to 79% of cases)
- Global developmental delayHPOHP:0001263
- Frequent (30% to 79% of cases)
- HepatomegalyHPOHP:0002240
- Frequent (30% to 79% of cases)
- HypotoniaHPOHP:0001252
- 1 of 10 reported patients
Genes
1 gene
Germline variants in the gene encoding each protein, as classified by GenCC submitters, each in their own words. Limited, disputed and refuted submissions are listed too.
- MMUTHGNC:7526
- Definitive · ClinGen · Autosomal recessive · 2019
- Definitive · G2P · Autosomal recessive · 2015
- Definitive · Natera · Autosomal recessive · 2023
- Strong · Labcorp Genetics (formerly Invitae) · Autosomal recessive · 2022
- Strong · PanelApp Australia · Autosomal recessive · 2025
Where it sits
Other names
4 names
Resolves to: methylmalonic aciduria due to methylmalonyl-CoA mutase deficiency
- Also called
- methylmalonic acidemia due to methylmalonyl-CoA mutase deficiencymethylmalonyl-CoA mutase deficiencymethylmalonyl-Coenzyme A mutase deficiencyvitamin B12-unresponsive methylmalonic aciduria